A conventional data storage array includes storage processors and storage devices. During operation, the storage processors respond to input/output (I/O) requests (e.g., Small Computer System Interface or SCSI commands) from one or more host computers by storing host data into the storage devices and/or loading host data from the storage devices.
Some conventional data storage arrays may include different storage tiers such a high-speed storage tier of flash drives, a moderate-speed storage tier of Serial Attached SCSI or SAS drives, and a low-speed storage tier of near-line SAS drives. For such an array, the flash drives of the high-speed storage tier typically form a first Redundant Array of Independent Disks or RAID group for frequently accessed host data, the SAS drives of the moderate-speed storage tier typically form a second RAID group for less frequently accessed host data, and the near-line SAS drives of the low-speed storage tier typically form a third RAID group for infrequently accessed host data.